The CHI, a new Fastbus interface and processor

Müller, H.; Berners‐Lee, Tim; Bogaerts, A.; Burckhart, D.; Divià, R.; Hollingworth, K.; McLaren, R. A.; Praag, A. van

doi:10.1109/23.106645

Cited by 12 publications

(15 citation statements)

References 4 publications

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“…For fixed α j , namely for a given eigenstate of MΠ M , the left and right moving modes Ψ (±) correspond to different branches of the exact solution of the vacuum string cosmology equations [2,3,13,15,16,19] a j = a j0 |t/λ s | ±α j ,…”

Section: Branch Changing As Wave Reflectionmentioning

confidence: 99%

Graceful exit in quantum string cosmology

1996

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We write an O(d,d)-covariant Wheeler-De Witt equation in the ($d^2+1$)-dimensional minisuperspace of low-energy cosmological string backgrounds. We discuss explicit examples of transitions between two duality-related cosmological phases, and we find a finite quantum transition probability even when the two phases are classically separated by a curvature singularity. This quantum approach is completely free from operator ordering ambiguities as a consequence of the duality symmetries of the string effective action.Comment: 16 pages, LATEX. A complete collection of papers and references on the pre-big-bang scenario in string cosmology is available at http://www.to.infn.it/teorici/gasperini

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Section: Branch Changing As Wave Reflectionmentioning

confidence: 99%

Graceful exit in quantum string cosmology

1996

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“…We show that separation of variables occurs in this case. It turns out that these moduli behave like "rolling radii" [12] which constitute fundamental cosmological solutions in weakly coupled string theory. Unlike those rolling radii which represent scale factors of homogeneous, isotropic spaces, here they measure the separation of the two walls of the three-brane and its worldvolume size (which, at the same time, is the size of "our" three-dimensional universe).…”

Section: Introductionmentioning

confidence: 99%

“…characteristic for rolling radii solutions[12] which are fundamental cosmological solutions of weakly coupled heterotic string theory. Comparison of the equations of motion(4.19) indeed shows that the scale factors α behave like rolling radii.…”

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confidence: 99%

Cosmological solutions of Hořava-Witten theory

1999

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Article (Published Version) http://sro.sussex.ac.uk Lukas, André, Ovrut, Burt A and Waldram, Daniel (1999) Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. We discuss cosmological solutions of Hořava-Witten theory describing the strongly coupled heterotic string. At energies below the grand-unified scale, the effective theory is five, not four, dimensional, where the additional coordinate parametrizes an S 1 /Z 2 orbifold. Furthermore, it admits no homogeneous solutions. Rather, the static vacuum state, appropriate for a reduction to four-dimensional Nϭ1 supersymmetric models, is a BPS domain wall pair. Relevant cosmological solutions are those associated with this BPS state. In particular, such solutions must be inhomogeneous, depending on the orbifold coordinate as well as on time. We present two examples of this new type of cosmological solution, obtained by separation of variables rather than by exchange of the time and radius coordinates of a brane solution, as in previous work. The first example represents the analogue of a rolling radii solution with the radii specifying the geometry of the domain wall pair. This is generalized in the second example to include a nontrivial ''Ramond-Ramond'' scalar. Cosmological solutions of Hořava-Witten theory

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“…It follows that the assumption of a Friedmann-Robertson-Walker (FRW) behaviour may be hindering important aspects of the early dynamics and other cosmological issues traceable to that era. Thus motivated we have relaxed the requirment of spatial isotropy in the FRW-type of symmetry in order to study (spatially) homogeneous models as background space-times for string theory [2], [3]. We have found that the one-loop beta-function equations in four dimensions admit an entire class of solutions representing homogeneous but not necessarily isotropic space-times.…”

Section: Introductionmentioning

confidence: 99%

“…From experience in general relativity we know that searching for the general solution to the system of Eqs. (1)(2)(3) or equivalently (8)(9)(10) is a hopeless and perhaps meaningless enterprise. Without any underlying symmetry [7], [8] or other physical input, such a coupled system of non-linear differential equations can supply an immence plethora of configurations representing chaotic or other intractable excitations, which would have little or nothing to do with the real world.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic spacetimes in homogeneous string cosmology

1995

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The dynamics of the early universe may have been profoundly influenced by spatial anisotropies. A search for such backgrounds in the context of string cosmology has uncovered the existence of an entire class of (spatially) homogeneous but not necessarily isotropic space-times, analogous to the class of Bianchi-types in general relativity. Configurations with vanishing cosmological constant but with non-vanishing dilaton and antisymmetric field are explicitly found for all types. This is a new class of solutions, whose isotropy limits reproduce all known and, further, all possible FRW-type of models in the string-cosmology context considered. There is always an initial singularity and no inflation. Other features of the general solutions, including their behaviour

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The CHI, a new Fastbus interface and processor

Cited by 12 publications

References 4 publications

Graceful exit in quantum string cosmology

Graceful exit in quantum string cosmology

Cosmological solutions of Hořava-Witten theory

Anisotropic spacetimes in homogeneous string cosmology

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